Wednesday, November 26, 2008

Galileo and the Discovery of a New World

2009 will be the International Year of Astronomy, commemorating the 400th anniversary of Galileo Galilei's groundbreaking astronomical discoveries with the then new telescope.

It's in this context that the University Heidelberg is organising a series of public lectures, Galilei's first glimpse through the telescope and its consequences today. So, a few days ago I spent a very entertaining evening in the magnificent "Alte Aula" of the university (photo here), listening to a talk by historian of science William Shea of the Cattedra Galileiana di Storia della Scienza, Università degli Studi di Padova, on Galileo and the Discovery of a New World.

Shea explained the main astronomical discoveries of Galileo, and also told quite a few entertaining side notes. For example, Galileo had no real understanding of the detailed workings of his telescope. On the other hand, he was an accomplished artist, who composed his famous drawings of the moon from partial views of the moon disc, as his telescope didn't show the whole moon at once.

If you are interested in a compact and entertaining introductory lecture about Galileo the astronomer, you might want to check out Shea's talk (it's in English, contrary to all the German text on the web page).



  1. Yeah, Galileo's amazing journey into changing the whole idea of the universe. I wish I could look through that telescope (not the first one ever, but the most powerful to that time and first used seriously on the sky.) I wonder how good the image quality was. Certainly not achromatically corrected (but with an f-number around maybe 15, not as bad as you'd think at only 32x.)

    This from the link is interesting, in showing that if the "right person" isn't looking then it doesn't really move the game:

    The first telescopic observations of the Moon on record were carried out by the englishman [sic] Thomas Harriot (ca. 1560-1621), on the evening of July 26 1609. However, based on his extant correspondence as well as entries in his notebooks, as in the case of sunspots Harriot did not appear to have drawn any particular physical significance from what he saw.

  2. Hi Stefan,

    Thanks for the heads up on next year being devoted to Astronomy and be assured as like many I’ll be looking forward to what that might bring. I only wish I were in Heidelberg as to attend some of these public lectures for myself. Also thanks for the link to Prof. Shea’s talk which I found very interesting, with him hinting that Galileo was three parts genius coupled to one part con man. I’ve read this before where Galileo has been held to task in part for his own demise, with Shea himself being one of the major promoters of such a view.

    None the less, as like with even Newton, scientists as us all are only human, being thus subject to both the strengths and weaknesses that accompany in being so. I think however we should remember them for their contributions more so then their failings. At the same time I do find it important to consider those involved including all the warts, since it affords one a more rounded perspective as to who they were and how they came to what they discovered. It also serves as to prevent them from being canonized, for just as it’s considered a key component in science, doubt should be always insisted to be extended to its practitioners, along with their conclusions.

    In the end, what I find as most important, is recognizing what they shared in common was a fascination with the mysteries presented by the natural world and a strong desire to resolve some of them, in the attempt to understand as much of it as one can. Prof. Shea by way of this lecture, brings to remind that far too much emphasis is placed upon what science can materially give us and too little of what it can lend to our understanding of the world, along with our place within it and the promise by way of the potential it holds.



    P.S. As a little Canadian connection, Prof. Shea taught previously at both the University of Ottawa and McGill in Montreal before taking on his current position at Padova.

  3. The "Alte Aula" is really an impressive location. I never fully realized how valuable it is to have a sense of being embedded into history. Growing up in Germany one gets so used to all these historic buildings that I came to see them just as 'old stuff'. Living on the Westcoast however, I came to miss this sense of being part of the story of human history.

  4. Hi Neil,

    Shea mentions in his talk that the telescope Galileo used in 1609 was made from high-quality Murano glass (5:40), had a magnification of about 15 times (8:35) and a field of view of about 12 minutes (9:30), so that he could see just one third of the moon at one time. Shea and his students have rebuilt such a telescope from old Murano glass lenses (35:00).

    Thanks for bringing up Thomas Harriot. That's an interesting story, which is mentioned by Shea in his talk (11:30). Harriot had a telescope with a magnification of about 6 times, and indeed, he was the first astronomer to observe the moon through a telescope. But it seems that he could not interpret what he saw as features of the rugged surface of the moon. In fact, Shea says, the British ambassador in Padova sent a copy of Galileo's 1610 report "Sidereus Nuncius" to the King of England on the very day of publication, and the king sent it on to Harriot. Seeing Galileo's drawings of the moon made Harriot actually recognize what he had seen already before, it seems.

    Cheers, Stefan

  5. Hi Phil,

    I'm glad that you liked the talk! On listening to it again, I must say that first few minutes may be a bit slow and a bit strange, as one does not see the slides Shea is looking at. But then, he has some really entertaining things to say - for example, the twelve preprints sent out to professors to get him a job (2:50), that he didn't know exactly how the telescope worked, as he didn't read Kelpler's Dioptrics (6:00), the students who used to buy portraits of their professors (15:50), "applied science" (that is, astrology - 10:55), or the invention of binoculars fixed to a helmet (33:50).

    What i found most fascinating is the story of the discovery of the moons of Jupiter (18:45 onwards), which took him a few days of observation to realize what he had seen, and the relevance of moons at a planet as an counter argument (25:50) to the objections raised against Copernicus "outrageous" argument that the earth may be moving at enormous speed around the sun.

    Cheers, Stefan

  6. Dear Bee,

    the Alte Aula is very impressive indeed! It was by chance that the talk took place there, however. All other talks (I have not been to any other, though) are in the "Neue Aula", which looks more or less like the Studentenhaus in Frankfurt.

    Cheers, Stefan

  7. Hi Stefan,

    Yes I also liked all of those points you mentioned as it served to put flesh on the bones so to speak. In particular I enjoyed as to the reason he didn’t read Kepler was that he only read new papers in which he was cited; and we think the world has changed:-) On the other hand he gave Galileo credit for his artistic skill and how that increased his powers of observation, which of course are so important to science.

    The story about Newton and the apple is meant to emphasis this for he was not the first to see one fall to the ground, yet rather the first to realize what significance that held in relation to the celestial motion. One could say that Einstein’s thought experiments are observations of sorts, only purely of those perceived in the mind.

    Yes it is lectures like Shea’s I enjoy most where a scientist is the subject because they show that discoveries are not just resultant of the powers of their minds, yet also by reason of the nature of their characters. This is what your other commenter Plato would call the emotive aspect of discovery and I for one would agree.



  8. Follow up for the sake of history: eventually, Galileo did make a telescope of about 32x power, IIRC. (I think, the one used for most observations of Jupiter and those moons, crescent of Venus, etc.) He put it in terms of area; "1,000 times the area". This way of talking is still used by some makers of cheap binoculars and telescopes to make the magnification seem more, but Galileo was just referencing the obvious fact of expansion in two dimensions of an image plane.



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